extemporise vs British spelling

extemporise is not a noun while British spelling is a noun.

Word	Noun	Adjective	Verb	Adverb
extemporise	No	No	Yes	No
British spelling	Yes	No	No	No

extemporise (noun)	British spelling (noun)
	English orthography used in the UK, Ireland and most of the Commonwealth (characterized by 'analyse', 'centre' and 'useable')

extemporise (verb)	British spelling (verb)
perform without preparation